PSI - Issue 60

Rosy Sarkar et al. / Procedia Structural Integrity 60 (2024) 75–92 Rosy Sarkar/ Structural Integrity Procedia 00 (2019) 000 – 000

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Figure 16 Ratcheting strain with number of cycles at various displacements

4.3 Comparison and Discussion The initiation of ratcheting is estimated using three ways: OPD given in ASME code, EID given in RCC MR code, and numerical simulation based on the FE method. The stresses extracted by FE analysis in the elastic route have been used to estimate the initiation of ratcheting using OPD and EID. The comparison of initiation of ratcheting at room temperature by various routes is shown in Figure 17. OPD does not predict ratcheting at 7-bar pressure, whereas EID predicts initiation of ratcheting at a displacement of 127 mm. Elasto-perfectly plastic analysis predicts initiation of ratcheting at 35 mm, which is significantly lower than that predicted by the elastic route.

Figure 17 Initiation of ratcheting at room temperature by various routes